Ice, Ice Everywhere
The ice sheet dominates Greenland, covering almost 2 million square kilometers and more than 2 miles (3 kilometers). If this ice sheet was to melt, sea levels would rise around the world by some 20 feet (7 meters). Glaciers flowing from the icesheet flow to the coast and carve out the remarkable mountain ranges that form Greenland’s coasts. These extend right down to the sea at the heads of dramatic fjords where they discharge their loads as giant icebergs of all sorts of fantastic shapes, sizes and colors. Greenland produces more icebergs than any other place in the world!
Icebergs are calved from inland glaciers, icebergs are 'made of' fresh water, and the average age of the ice is thought to be about 15,000 years! Typically only one-ninth of the iceberg can be seen above the water's surface. The ice of an iceberg is rock hard, and the icebergs are of all shapes and sizes, sometimes rising hundreds of feet above sea level.
Eventually icebergs from Greenland make their way out to the open ocean where they drift southwards into the Atlantic. They begin to crumble under the strength of the summer sun and rising temperatures further south, and produce a great many 'bergy bits' and 'growlers'.
Get the full iceberg story from our partner "Beyond Penguins and Polar Bears" >>
Sea ice is also called 'pack ice.' Sea ice forms from frozen seawater, not compacted snow. Sea ice is dynamic and forms in stages, with different names for each stage. It changes with the seasons, and it is almost always on the move.
Sea ice forms when the temperature of the ocean surface falls below 29˚F (-1.89 Celsius). On a lake, with its calm surface, ice forms in a gradually thickening sheet. The ocean surface on the other hand is frequently stirred by waves and this leads to different ice...
In turbulent water, tiny disc-shaped crystals of ice form into a substance called frazil. As they are stirred through the sea surface, the crystals give the water a greasy appearance, hence the name 'grease ice'. Another form that sea ice takes as it grows is shuga, composed of small chunks of ice that undulate on the surface of the water in a sheet. When the ice clumps together, it forms rounded sheets with upturned edges, called pancake ice. The pancakes damp down the waves somewhat, allowing pancakes to consolidate into larger pancakes. Eventually, the pancake ice freezes into floes - larger sheets of sea ice floating on the water's surface.
There are two types of pack ice: first-year ice and multi-year ice. First-year ice freezes in autumn or early winter and melts in the summer. Typically, first-year ice is between a foot to six feet thick (30 cm - 2 meters). Multi-year ice is simply pack ice that has survived at least one winter!
A smaller fraction of the polar sea ice grows along shorelines and in enclosed bodies of water such as bays. This is called land fast ice.
Learn more about sea ice from the National Snow and Ice Data Center >>
Importance of sea ice in Greenland
The frozen sea ice is the highway for traveling by dog team and snow mobiles. This is how hunters travel by dog team to get to their hunting spots, and enormous distances can be covered relatively easily traveling between communities -- So, the sea ice is all important in keeping the far-flung settlements of Greenland connected.
It is easy to wonder why East Greenland is so isolated with so few people living there. The reason is the behavior of the sea ice. The eastern side is obviously not easy to get to overland, as it takes the crossing of the entire ice sheet which is hundreds of miles (and kilometers) wide. But also, it is very difficult to get there "by sea ice." A huge stream of Polar ice and icebergs, called the Great Ice, flows from the polar ice cap in the Arctic ocean north of Greenland southwards on the eastern side of Greenland on currents along the coast -- this flow is so powerful that is basically bars access from the East! On the upside, this isolation is largely the reason why ancient skills and traditions really flourish on this area, because it has somewhat been hidden from influence, even from the rest of Greenland!